1
Screening Aid
This CAPS (Cooperative Agricultural Pest Survey) screening aid produced for and distributed by\
:
USDA-APHIS-PPQ National Identification Services (NIS)
This and other identification resources are available at: http://caps.ceris.purdue.edu/taxonomic_services
Joseph Benzel
1) Identification Technology Program (ITP) / Colorado State University, USDA-APHIS-PPQ-Science & Technology (S&T), 2301 Research
Boulevard, Suite 108, Fort Collins, Colorado 80526 U.S.A. (Email: itp@USDA.gov)
The pine sawyer beetles ( Monochamus spp.) are a widespread genus of
longhorn beetles with several members of economic importance. Within
this group are two species that are considered potentially invasive
pests: the small white-marmorated longhorned beetle ( Monochamus
sutor ) (Fig. 1) and the Japanese pine sawyer ( Monochamus alternatus )
(Fig. 2). Monochamus alternatus feeds primarily on pines ( Pinus ) but
will attack a variety of conifers and some deciduous trees. Monochamus
sutor attacks a variety of conifer species including fir ( Abies ), larch
(Larix ), and spruce ( Picea ). Both species are known to carry the pine
wood nematode ( Bursaphelenchus xylophilus ) and other phytoparasitic
nematodes that are capable of killing trees and spreading bacterial
diseases. The beetle itself feeds on the phloem as a larvae and in the
crown as an adult (Figs. 3-4) but is unlikely to directly kill its host.
Monochamus belongs to the family Cerambycidae, which are known
as the longhorned beetles. Members of this family are recognized by
their highly elongate antennae, in males sometimes reaching twice the
length of body. Monochamus belongs to the subfamily Lamiinae which
is distinguished by its hypognathus head, acute palpi, and obliquely
sulcate anterior tibia.
The genus Monochamus contains over 100 species and is found
worldwide. Eight species and six additional subspecies occur in the U.S.
Monochamus adults are identified by large acute lateral tubercles on
the pronotum, coursely rougose elytral bases, and elongate front legs in
the male. Neither M. alternatus nor M. sutor have been detected in the
United States.
This aid is designed to assist in the sorting and screening of M.
alternatus and M. sutor suspect adults collected in Lindgren funnel traps
and by visual surveys in the continental United States. It covers basic
Sorting of traps, First Level, and Second Level screening, all based on
morphological characters. Basic knowledge of Coleoptera morphology
is necessary to screen for M. alternatus and M. sutor suspects.
Fig. 1: Monochamus sutor on
tree (photo by Stanislaw Kinelski,
Bugwood.org).
Fig. 2: Monochamus alternatus
on tree (photo by William M.
Ciesla, Forest Health Management
International, Bugwood.org).
Version 3
6 July 2015
Coleoptera Cerambycidae
Pine Sawyer Beetles
Monochamus sutor (Linnaeus) and M. alternatus Hope
2
Sorting
Insects collected during Monochamus surveys should be sorted initially for the presence of beetles of
the appropriate size, color, and shape.
1. Beetles are between 15 mm (0.6 inches) and 28 mm (1.1 inches) in length.
2. Beetles have highly elongate antennae, over twice body length (Fig. 5).
3. Beetles are black, or mottled brown with white patches (Figs. 11 & 14).
Beetles meeting these requirements should be forwarded to Level 1 Screening (Page 3).
Fig. 3-4: Monochamus sp. galleries infected with
bluestain fungi and containing larvae (top) and pupae
(bottom). Despite their large size, Monochamus do
little direct damage the host tree. They burrow in the
phloem and heartwood where they feed on wood and
symbiotic fungi. Most trees that are killed die as the result
of infection by parasites vectored by the beetle. These
include bluestain fungus, the pine wood nematode, and a
variety of pathogenic bacteria (photos by Lacy L. Hyche,
Auburn University, Bugwood.org).
Fig. 5-6: Lateral views of male (top) and female (bottom)
Monochamus sp. Monochamus is a sexually dimorphic
genus with males having antennae and forelegs
significantly longer than those of females. Conversely,
the overall body size of females is usually greater than
that of males, although some overlap does occur.
Fig. 5: male Monochamus sp.
Fig. 6: female Monochamus sp.
Coleoptera Cerambycidae
Pine Sawyer Beetles
Monochamus sutor (Linnaeus) and M. alternatus Hope
3
Fig. 10: Dorsal view of Monochamus
marmorator . Note the pair of large
horns on the pronotum (circled), the
coarsely rougose elytral bases, and
the uniformly pubescent elytra. Many
species have elaborately patterned
pubescence.
Level 1 Screening
Suspect adults should be pinned and properly labeled. Level 1
Screening is based on characteristics of the head, tarsal claws,
general dorsal surface, and antennae. It is designed to separate
Monochamus from related genera.
Head
The heads of the subfamily Lamiinae are vertical with the genial
margin directed posteriorly rather than ventrally (Fig 7).
Tarsal Claws
The tarsal claws of Monochamus are divergent (Fig. 8) rather than
being divaricate or bifid.
Antennae
The antennal scape of Monochamus has a distinct carinate ring
called a “circatrix” at the apex (Fig. 9).
General Dorsal Features
The prothorax of Monochamus bears a pair of large prominent
lateral tubercles (Fig. 10). The elytral bases are coarsely rougose
and the elytra themselves are uniformly covered with pubescence
(Fig. 10). The related genus Anoplophora (which includes the
Asian longhorned beetle - ALB) is always black in color and has
pubecence only in distinct patches.
Specimens meeting these requirements should be forwarded to
Level Two Screening.
Fig. 7: Head of Monochamus sp. In
the Lamiinae the head is vertically
oriented with the mouthparts directed
ventrally, and the genal margin is
directed posteriorly.
Fig. 8: Tarsal claws of Monochamus
sp.
Fig. 9: Antennal base of Monochamus
sp. The scape has a distinct cicatrix at
its apex (circled).
Coleoptera Cerambycidae
Pine Sawyer Beetles
Monochamus sutor (Linnaeus) and M. alternatus Hope
4
Level 2 Screening
Level 2 screening is designed to separate M. alternatus and M. sutor suspects from native Monochamus .
Screening is based on characters of the elytra and scutellum as well as \
general notes on size.
Monochamus spp. are sexually dimorphic (Figs. 5-6), with the male having antennae twice as long as the
body and females having antennae 1.5 times as long as the body.
Monochamus sutor
Monochamus sutor (Fig. 11) bears a close resemblence to the native M. scutellatus (Fig. 12) . Both beetles
are black in color which distinguishes them from other native Monochamus (Fig. 13). The apices of their
elytra are rounded and unarmed by spines at the suture (Fig. 20). The two species can be distinguished
by the larger amounts of pubescence on the elytra of M. sutor. Usually this pubescence is yellow in color
and occurs in dense patches. In M. scutellatus the pubescence is more evenly distributed and is snow
white in color. Both species have a densley pubescent scutellum where the difference in color of the
pubescence can be easily observed (Figs. 25-26).
Monochamus alternatus
The elytral apex of M. alternatus (Fig. 21) is more narrowly rounded than that of M. sutor (Fig. 20) .
Monochamus alternatus is reddish brown to black in color with two broken stripes of orange pu\
bescence
on the pronotum (Fig. 27). Two native species, M. carolinensis (Fig. 15) and M. titillator (Fig. 16) bear
a close resemblence to M. alternatus (Fig. 14) . The three can be distinguished by the unarmed and
somewhat flattened elytral apicies of M. alternatus compared to the broad tooth seen in M. carolinensis
and the narrow conical tooth of M. titillator (Figs. 21-23) . Other non-target species (Figs. 17-19) lack the
tooth entirely (e.g., Fig. 24).
Fig. 11: Monochamus sutor (target) Fig. 12: Monochamus scutellatus Fig. 13: Monochamus obtusus
Coleoptera Cerambycidae
Pine Sawyer Beetles
Monochamus sutor (Linnaeus) and M. alternatus Hope
5
Level 2 Non-targets
Fig. 14: Monochamus alternatus (target)
(Photo by Steven Valley, Oregon
Department of Agriculture, Bugwood.org).
Fig. 15: Monochamus carolinensis. Fig. 16: Monochamus titillator.
Fig. 19: Monochamus notatus. Fig. 18: Monochamus clamator. Fig. 17: Monochamus mutator.
Coleoptera Cerambycidae
Pine Sawyer Beetles
Monochamus sutor (Linnaeus) and M. alternatus Hope
6
Level 2 Non-targets
Suspect M. sutor (black cerambycids with vertical heads, a
circatrix on the antennae, broadly rounded elytral apicies, and
small spots of yellow pubescence) and M. alternatus (red-brown
cerambycids with vertical heads, a circatrix on the antennae,
narrowed but unarmed elytral apicies, and two stripes of orange
pubescence on the pronotum) should be sent forward for
identification. Specimens must be labeled and carefully packed to
avoid damage during shipping.
Figs. 25-26 (left): Scutellums of M. sutor and
M. scutellatus . Note the difference in the color
of the pubescence.
Fig. 26: Monochamus scutellatus.
Fig. 22: Monochamus carolinensis.
Fig. 25: Monochamus sutor (target).
Fig. 21: Monochamus alternatus (target).
(Photo by Steven Valley, Oregon
Department of Agriculture, Bugwood.org).
Fig. 23: Monochamus titillator .
Fig. 27 (below) Pronotum of Monochamus
alternatus . Note the two stripes of orange
pubecence. (Photo by Steven Valley,
Oregon Department of Agriculture,
Bugwood.org).
Fig. 20: Monochamus sutor (target).
Fig. 24: Monochamus clamator
Figs. 20-24: Elytral apicies of
various Monochamus spp. The
apex of M. sutor is broadly
rounded while that of most other
Monochamus are more acute
and often armed with spines
as seen with M. carolinensis
and M. titillator . The apex of
M. alternatus is narrowed but
unarmed.
Coleoptera Cerambycidae
Pine Sawyer Beetles
Monochamus sutor (Linnaeus) and M. alternatus Hope
7
Key and References
Key to Sort and Screen M. sutor and M. alternatus Suspects in the United States
1. Beetles approxmately 15-28 mm long; antennae significanly longer than body and with distinct
circatrix on scape (Fig. 9); coloration black or red-brown with uniformly pubescent elytra,
mouthparts directed ventrally (Fig. 7); tarsal claws divergent (Fig. 8) ............................................. 2
1’. Beetles larger or smaller than 15-28 mm long; antennae not significantly longer than body or
without distict circatrix; color not black or red brown or without uniformly distributed pubescence
on the elytra; mouthparts directed forward; or tarsal claws divaricate or bifid. ............... Not suspect
2. Elytral apices rounded (Fig. 20); body usually black ...................................................................... 3
2’. Elytral apices flattened or armed with tooth (Fig. 21); body usually reddish brown.. ....................... 4
3. Body with large amount of pubescence; patches of pubescence yellow in color
(Fig. 25) ........................................................................\
......................................... M. sutor suspect
3’. Body with less pubescence, patches of pubescence white in color (Fig. 26) ................ Not suspect
4. Pronotum with two stripes of orange pubescence (Fig. 27); elytral apices not armed with tooth
(Fig. 21). ........................................................................\
................................ M. alternatus suspect
4. Pronotum without stripes of orange pubescence; elytral apex armed with tooth (of various forms)
(Figs. 22-23) ........................................................................\
........................................... Not suspect
Citation
Benzel, J. S. 2015. Screening aid: Pine sawyer beetles, Monochamus sutor (Linnaeus) and M. alternatus Hope. Identification
Technology Program (ITP), USDA-APHIS-PPQ-S&T, Fort Collins, CO. 7 pp.
References for more information on Monochamus sutor, M. alternatus , and non-targets
CERIS. 2011 . Exotic Wood Borer/Bark Beetle Survey Reference: Monochamus sutor. https://caps.ceris.purdue.edu/node/506.
CERIS. 2013 . Exotic Wood Borer/Bark Beetle Survey Reference: Monochamus alternatus. https://caps.ceris.purdue.edu/
node/506.
Lingafelter, S. W. 2007. Illustrated key to the longhorned woodboring beetles of the eastern Unit\
ed States. The Coleopterists
Society. North Potomac. Maryland. pp. 7-15.
Lingafelter, S. W. and Hoebeke, E. R. 2002. Revision of the genus Anoplophora (Coleoptera: Cerambycidae). The
Entomological Society of Washington. Washington D.C. pp. 30-32.
Linsley, E. G. and Chemsak, J. A. 1984. The Cerambycidae of North America, Part VII, No. 1: Taxonomy and Classification
of the Subfamily Lamiinae, Tribes Parmennini Through Acanthoderini . Entomology: Volume 102. University of California Press.
Berkeley, California pp. 49-78
Turnbow, R. H. and Thomas, M. C. 2002 . Family 120. Cerambycidae, pp 568-601. In, Arnett R. H., American Beetles: Volume
II. CRC Press. Boca Raton, Florida.
Acknowledgments
Funding for this project was provided to J. S. Benzel through section 10201 of the FY2014 Farm Bill. I would like thank Terrence
Walters (USDA-APHIS-PPQ-S&T ITP) and USDA-APHIS-PPQ National Identification Services for support of this work and
access to imaging equipment. Boris Kondratieff, Donald Bright, and Todd Gilligan (Colorado State University) provided advice on
species identification, image editing, and screening aid formatting.
Coleoptera Cerambycidae
Pine Sawyer Beetles
Monochamus sutor (Linnaeus) and M. alternatus Hope
